Cercariform cells: are they specific for transitional cell carcinoma?

Abstract

Cercariform cells (CCs) recently have been described as a significant clue to the cytologic diagnosis of transitional cell carcinoma (TCC). The CC is a single tumor cell with a nucleated globular body and a unipolar cytoplasmic process with a nontapering, flattened, or bulbous end. To determine the specificity of CCs in FNAs, 45 cases of poorly differentiated malignant epithelial neoplasms (PDMEN) and 11 cases of metastatic TCC were reviewed, and the number of CCs present in each case was counted. All cases had 1-19 air-dried Diff-Quik stained slides, 1-6 ethanol fixed Papanicolaou stained slides, and one Millipore filter preparation. CCs were identified in 16 of 45 cases of PDMEN (36%). Nine cases had 1-4 CCs, 3 cases had 5-9 CCs, 2 cases had 10-19 CCs, and 2 cases had >20 CCs. The 2 cases with >20 CCs included PDMEN of the lung and metastatic PDMEN in the liver. CCs were identified in all 11 cases of metastatic TCC. Two cases had 1-4 CCs, 3 cases had 5-9 CCs, 1 case had 10-19 CCs, and 5 cases had >20 CCs. The metastatic sites included the lymph nodes (six cases), liver (three cases), lung (one case), and sacrum (one case). The finding of a few CCs is not specific for TCC. CCs were observed in 16 of 45 cases of PDMEN (36%). The presence of >20 CCs is significantly more likely to occur in metastatic TCC (5 of 11 cases; 45%) than PDMEN (2 of 45 cases; 4%) (P<0.001). If no CC is identified in an FNA, it is unlikely that the case represents a metastatic TCC because all 11 cases of metastatic TCC in the current study had at least 1 CC. It is interesting to note that all 11 cases of metastatic TCC were found to have CCs on the filter, suggesting that the morphology of the CC is not a smearing artifact.